unnecessary-empty-iterable-within-deque-call (RUF037)

Fix is always available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for usages of collections.deque that have an empty iterable as the first argument.

Why is this bad?

It's unnecessary to use an empty literal as a deque's iterable, since this is already the default behavior.

Example

from collections import deque

queue = deque(set())
queue = deque([], 10)

Use instead:

from collections import deque

queue = deque()
queue = deque(maxlen=10)

References

• Python documentation: collections.deque